The overall aim of our research is to gain an increased understanding of the nature and functions of B lymphocytes, and their interactions with antigen molecules in the induction of antibody formation and immunological tolerance. Specifically; 1. We aim to determine by what mechanisms immature B cells are subject to clonal abortion, i.e. tolerogenesis by very low antigen concentrations. 2. We plan to improve methods for the isolation and cloning of hapten-specific lymphocytes. 3. We will study the generation of diversity amongst differentiating "pre-B" lymphocytes; and 4. We will seek to determine the characteristics and functions of IgD-bearing B cells as opposed to those lacking IgD.